Thyssenkrupp Steel Europe Ag

Thyssenkrupp Steel Ag

Thyssen Krupp Ag

Sabine Zeizinger

Norbert Schaffrath

Michael Peters

Gernot Nothacker

Manfred Meurer

Rudolf Schoenenberg

Wilhelm Warnecke

Ronny Leuschner

Michael Ullmann

Marc Blumenau

Jens-Ulrik Becker

Thomas Heller

Richard Georg Thiessen

Martin Norden

Karsten Machalitza

Jian Bian

Klaus Josef Peters

Rudolf Schonenberg

Rudolf Schönenberg

Sridhar Palepu

Thomas Rieger

Oliver Bulters

Oliver Bülters

A device minimizes or eliminates surface flaws caused by metal dust on a metal strip to be coated in a continuous hot-dip coating process, where at least some segments of the metal strip to be coated are conveyed through the device in an axial direction. The device may comprise a blowing/sucking unit with blow-in openings for applying protective gas to the metal strip, which blow-in openings are positionable on first and second sides of the metal strip. The blowing/sucking unit may further include suction openings for extracting protective gas laden with metal vapor and/or metal dust, which suction openings are positionable on the first and second sides of the metal strip. The blowing/sucking unit may have a blow-in region in which the blow-in openings are arranged, and a suction region downstream of the blow-in region in which the suction openings are arranged.

Device and method for improved extraction of metal vapor

The invention relates to a method and to an apparatus for avoiding surface defects, which are caused by zinc dust, on galvanized metal strip in continuous strip galvanization, in which metal strip which is to be galvanized and is heated in a continuous annealing furnace is moved through a furnace pipe in protective furnace gas and is immersed into a zinc bath, wherein the furnace pipe is provided with injection openings via which the front side and the rear side of the metal strip can be acted upon with protective furnace gas, and wherein extraction openings for extracting protective furnace gas loaded with zinc vapor are arranged adjacent to the injection openings. The apparatus according to the invention is characterized in that a multiplicity of the injection openings are configured and arranged in the furnace pipe in such a manner that the protective furnace gas streaming out of said injection openings is directed onto that surface of the metal strip which faces the respective injection opening with an angle of impact within the range of 70&#xb0; to 110&#xb0;, wherein the distance between the respective injection opening and at least one extraction opening assigned thereto is selected in such a manner that, at a predetermined or predeterminable flow velocity of the protective furnace gas emerging from the respective injection opening, an entraining of protective furnace gas, which occurs during movement of the metal strip, in the direction of the zinc bath is opposed.

Method and device for avoiding surface defects caused by zinc dust in a continuous strip galvanising process

A flat steel product having a tensile strength of at least 1200 MPa and consists of steel containing (wt %) C: 0.10-0.50%, Si: 0.1-2.5%, Mn: 1.0-3.5%, Al: up to 2.5%, P: up to 0.020%, S: up to 0.003%, N: up to 0.02%, and optionally one or more of the elements 'Cr, Mo, V, Ti, Nb, B and Ca' in the quantities: Cr: 0.1-0.5%, Mo: 0.1-0.3%, V: 0.01-0.1%, Ti: 0.001-0.15%, Nb: 0.02-0.05%, wherein &#x3a3;(V, Ti, Nb)&#x2266;0.2% for the sum of the quantities of V, Ti and Nb, B: 0.0005-0.005%, and Ca: up to 0.01% in addition to Fe and unavoidable impurities. The flat steel product has a microstructure with (in surface percent) less than 5% ferrite, less than 10% bainite, 5-70% untempered martensite, 5-30% residual austenite, and 25-80% tempered martensite, at least 99% of the iron carbide contained in the tempered martensite having a size of less than 500 nm.

High-strength flat steel product and method for producing same

An apparatus and a method for the treatment of a flat steel product, taking place in throughput. The apparatus includes an indirectly heated annealing furnace chamber, a conveyor device for continuously conveying the flat steel product over a conveyor path leading from an entry to an exit of the annealing furnace chamber, and nozzle arrangements for feeding atmosphere gas, which is reactive in relation to the flat steel product, into the annealing furnace chamber. A controlled treatment of the flat steel product includes a first nozzle arrangement, from which a gas jet induces a first gas flow towards the entry of the annealing furnace chamber and sweeping over the surface of flat steel product to be treated. A second nozzle arrangement includes a gas jet which induces a second gas flow directed towards the exit of the annealing furnace chamber and sweeping over the surface of flat steel product.

Apparatus and method for the treatment of a flat steel product, taking place in throughput

A process for melt dip coating a strip of high-tensile steel with alloy constituents including zinc and/or aluminum includes the following steps. The strip is heated in a continuous furnace initially in a reductive atmosphere to a temperature of approximately 650&#xb0; C., at which the alloy constituents diffuse to the surface in small amounts. The surface, consisting predominantly of pure iron, is converted into an iron oxide layer by a short heat treatment at a temperature of up to 750&#xb0; C. in a reaction chamber which is integrated in a continuous furnace and has an oxidizing atmosphere. In a subsequent annealing treatment at a higher temperature in a reductive atmosphere, this iron oxide layer prevents the alloy constituents from diffusing to the surface. In the reductive atmosphere, the iron oxide layer is converted into a pure iron layer to which the zinc and/or aluminum are applied in the molten bath with optimum adhesion.

Process for melt dip coating a strip of high-tensile steel

A method for coating a flat steel product manufactured from a high strength steel with a metallic coating, wherein the flat steel product is initially subjected to a heat treatment, in order then, in the heated state, to be hot-dip galvanized with the metallic coating in a melting bath containing overall at least 85% zinc and/or aluminum. The heat treatment includes heating the steel product in a reducing atmosphere, followed by converting a surface of the flat product to an iron oxide layer by a heat treatment lasting 1 to 10 secs in an oxidizing atmosphere, followed by annealing in a reducing atmosphere over a period of time which is longer than the duration of the formation of the iron oxide layer such that the iron oxide layer is reduced at least on its surface to pure iron, followed by cooling the product to a melting bath temperature.

Method for melt immersion coating of a flat steel product made of high strength steel

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Mülheim, Germany

Sabine Zeizinger